I thought ST has written their own "driver" for this device, but I can't find it yet, and looking on ST's community forum, people didnt seem happy with the lack of documentation on this device ST software is here http://www.st.com/en/embedded-software/stsw-img005.html but free registration is requi...

All the Agilent sensors that I know do all the work and the chip is usually only an USB MCU that simply translate the information received from the chip to the driver using USB. This MCU can receive some commands like dpi change.
There are many Arduino libraries for these Agilent ADNS chips.